Apparent slip at a polymer-polymer interface

Abstract:

We consider a planar interface between strongly-segregated homopolymers subjected to steady shear in the plane of the interface. We develop a constitutive equation for stress relaxation in an inhomogeneous system for chains obeying Rouse dynamics. Using this equation, the interfacial viscosity for a symmetric blend is found to be $\zeta {b^2}/(6x{\upsilon _0})$ in agreement with a scaling prediction due to de Gennes, where $\zeta$ is the bead friction coefficient, b is the segment length, υ is the segment volume and χ is the Flory-Huggins interaction parameter driving the phase separation. We generalize our results to asymmetric blends and describe a phenomenological extension to entangled melts.